This invention relates in general to gas measuring devices and in particular to a new and useful solid state cell for measuring the activity of a component of a mixture.
The invention concerns a solid state cell for measuring the activity of a component in a mixture, especially for the determination of the partial pressure of a component of a gas mixture, with the use of a solid state ion conductor, which is in contact on one side with a reference phase and on the other side with a phase gas sensitive to the gas component to be determined, with lead electrodes provided at the reference phase and at the gas sensitive phase.
A solid state cell of this type has become known from German OS No. 29 26 172. In this solid state cell the ion conductor LiAlCl.sub.4 is provided for measuring the partial pressure of chlorine, for exmaple that has acting as a gas sensitive phase an addition of AlCl.sub.3 with which the solid state ion conductor is in phase equilibrium. The chlorine to be determined influences the gas sensitive phase and thereby the phase equilibrium between the gas sensitive phase and the ion conductor in such a manner that the activity of the mobile species is fixed at the boundary. An electromotive sorce (EMF) can be determined with the aid of one lead electrode, respectively, between the reference phase and the gas sensitive phase. But the observation was made that the adjustment of the EMF corresponding to the partial pressure of the gas to be determined frequently occurs only after a response time that is undesirably long for practical application.
It was also found that a stable measuring signal is established only after days, which fact does not allow the determination of quickly changing concentrations.